Validation of the Longitudinal Interval Follow-Up Evaluation for the Long-Term Measurement of Mood Symptoms in Bipolar Disorder

Abstract

The long-term burden of symptoms is an important outcome in bipolar disorder (BD). A method which has minimal burden of assessment uses a retrospective interview, the Longitudinal Interval Follow-up Examination (LIFE), although this may be subject to problems with recall. This study examines the relationship between the retrospective LIFE scale and concurrently-rated mood rating scales in two clinical trials of 18 months of psychotherapy for patients with BD. The Montgomery-Asberg Depression Rating Scale (MADRS) and Young Mania Rating Scale (YMRS) were administered every eight to nine weeks and the LIFE was carried out every 6 months. Correlations between scores on mood rating scales and at equivalent times on the LIFE were examined, as well as of potential clinical moderators. There were significant correlations between LIFE depression ratings and concurrent MADRS score (r = 0.57) and between LIFE mania ratings and YMRS score (r = 0.40). In determining “mild depression” on the MADRS, a receiver operating characteristics (ROC) analysis showed an AUC of 0.78 for LIFE scores. Correlations, particularly for depression scores, were high even when the LIFE rating was several months before the interview, suggesting that the LIFE has validity in examining the burden of mood symptoms over time, with relatively little burden of assessment. Future research should examine the relationship between symptom burden and quality of life measured in this way.